Polishing pad having abrasive grains and method for making the same

ABSTRACT

The present invention relates to a polishing pad having abrasive grains and a method for making the same. The polishing pad having abrasive grains includes a plurality of fibers, a plurality of abrasive grains and a high polymer. The fibers intersect each other to form a fiber matrix. The abrasive grains are attached to the fibers. The high polymer covers the fibers and the abrasive grains. The abrasive grains will not easily scratch a surface of a workpiece to be polished due to the flexibility of the fibers.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a polishing pad and a method for makingthe same, in particular, to a polishing pad having abrasive grains and amethod for making the same.

2. Description of the Related Art

In a conventional polishing method, a slurry is used together with apolishing pad. The slurry has a plurality of abrasive grains, which areused to polish a surface of a workpiece to be polished. The polishingpad has a plurality of pores, and the pores are communicated with eachother, such that the slurry is uniformly dispersed over a surface of thepolishing pad, so as to improve the polishing capability.

The conventional polishing method has the following disadvantages.During the polishing process, when the slurry flows through the pores,the abrasive grains of the slurry may easily block the pores, thusdegrading the polishing capability. Then, a dresser needs to be used todress the blocked pores and recover the polishing capability of thepolishing pad. However, the addition of such a step in the originalprocess will increase cost and lower efficiency.

In another conventional polishing method, a polishing pad havingabrasive grains is used. FIG. 1 shows a schematic view of a conventionalpolishing pad having abrasive grains disclosed in Taiwan PatentPublication No. I233384. The polishing pad 1 having abrasive grainsincludes a bottom layer 11 and a polishing layer 12. The polishing layer12 is disposed on the bottom layer 11, and has a resin 121 and aplurality of abrasive grains 122. The resin 121 covers the abrasivegrains 122, and has a polishing surface 1211. A portion of the abrasivegrains 122 is exposed to the polishing surface 1211 of the resin 121.

The conventional polishing pad 1 with abrasive grains has the followingdisadvantages. The polishing pad 1 having abrasive grains utilizes theresin 121 to fix the abrasive grains 122, so that during the polishingprocess, the abrasive grains 122 are fixed at the same position, abradethe workpiece to be polished with repetitive stress in a singledirection, and thus easily scratch the workpiece to be polished.Meanwhile, as the resin 121 is gradually worn, the area of the abrasivegrains 122 fixed within the resin 121 that are exposed to the polishingsurface 1211 becomes larger, and the problem of scratching grows worse.

Therefore, it is necessary to provide a polishing pad having abrasivegrains and a method for making the same, so as to solve the aboveproblems.

SUMMARY OF THE INVENTION

The present invention is directed to a polishing pad having abrasivegrains. The polishing pad comprises a plurality of fibers, a pluralityof abrasive grains and a high polymer. The fibers intersect each otherto form a fiber matrix. The abrasive grains are attached to the fibers.The high polymer covers the fibers and the abrasive grains.

The present invention is further directed to a method for making apolishing pad having abrasive grains. The method comprises the steps of:(a) providing a fiber matrix, in which the fiber matrix has a pluralityof fibers and a plurality of abrasive grains, the fibers intersect eachother, and the abrasive grains are attached to the fibers; (b) immersingthe fiber matrix in a high-polymer solution; and (c) performing a curingstep, such that the fiber matrix is covered with a high polymer.

Thereby, the abrasive grains may not easily scratch a surface of aworkpiece to be polished due to the flexibility of the fibers, and thepolishing pad has a desirable polishing capability due to the assistanceof an acid or alkali slurry containing no abrasive grains or anelectrolytic solution containing an electrolyte, thus avoiding theproblem in the prior art that the abrasive grains of the slurry blockthe pores of the polishing pad. Moreover, after the polishing pad isused in the polishing process, only a small number of abrasive grainsare left on the surface of the workpiece to be polished, which can beeasily washed away by a simple rinsing procedure, and the wastewater mayalso be easily treated.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a polishing pad having abrasive grains inthe prior art;

FIG. 2 is a schematic view of a polishing pad having abrasive grainsaccording to a first embodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of fibers of the polishingpad having abrasive grains according to the first embodiment of thepresent invention, in which the fibers are solid;

FIG. 4 is a schematic cross-sectional view of fibers of the polishingpad having abrasive grains according to the first embodiment of thepresent invention, in which the fibers are hollow;

FIG. 5 is a flow chart of a method for making the polishing pad havingabrasive grains according to the first embodiment of the presentinvention;

FIG. 6 is a schematic view of a polishing pad having abrasive grainsaccording to a second embodiment of the present invention;

FIG. 7 is a schematic cross-sectional view of fibers of the polishingpad having abrasive grains according to the second embodiment of thepresent invention, in which the fibers are solid;

FIG. 8 is a schematic cross-sectional view of fibers of the polishingpad having abrasive grains according to the second embodiment of thepresent invention, in which the fibers are hollow; and

FIG. 9 is a flow chart of a method for making the polishing pad havingabrasive grains according to the second embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2 shows a schematic view of a polishing pad having abrasive grainsaccording to a first embodiment of the present invention. The polishingpad 2 having abrasive grains comprises a plurality of fibers 21, aplurality of abrasive grains 22 and a high polymer 23. In otherapplications, the polishing pad 2 further comprises a bottom layer,which may be a glue layer or another composite layer.

The abrasive grains 22 are attached to the fibers 21, and the fibers 21intersect each other to form a fiber matrix 24. In this embodiment, thefibers 21 are solid, and the abrasive grains 22 are disposed on surfacesof the fibers 21 (as shown in FIG. 3). In other applications, the fibers21 may be hollow, and the abrasive grains 22 are disposed on surfaces ofthe fibers 21 (as shown in FIG. 4).

Preferably, the fibers 21 have a size of 0.001 to 6 denier. Preferably,the fibers 21 are made of a material selected from a group consisting ofa polyamide resin, polyethylene terephthalate (PET), polyester resin,nylon, polypropylene (PP), acrylic resin and polyacrylonitrile resin. Inthis embodiment, the fiber matrix 24 is a non-woven fabric. Preferably,the fiber matrix 24 is formed by chemical bonding, thermal bonding,mechanical bonding, dry carding, direct web-forming or wet web-forming.In this embodiment, the abrasive grains 22 have an average diameter of0.01 to 100 μm, and are made of a material selected from a groupconsisting of SiO₂ CeO₂, Al₂O₃, oxides of transition metals and oxidesof Group IIA metals.

The high polymer 23 covers the fibers 21 and the abrasive grains 22, andhas a first surface 231 and a second surface 232. Preferably, a portionof the fibers 21 and a portion of the abrasive grains 22 are exposed tothe first surface 231. The first surface 231 is a polishing surface. Inother applications, the high polymer 23 completely covers the fibers 21and the abrasive grains 22. After the polishing process has beenperformed for a period of time, and a portion of the high polymer 23 onthe first surface 231 (polishing surface) is removed, a portion of thefibers 21 and a portion of the abrasive grains 22 are exposed to thefirst surface 231. Alternatively, a portion of the high polymer 23 onthe first surface 231 is removed (for example, dressed or abraded) inadvance before the polishing process is performed, such that a portionof the fibers 21 and a portion of the abrasive grains 22 are exposed tothe first surface 231, and then the polishing process is performed. Inthis embodiment, the high polymer 23 is an intercommunicated porous highpolymeric elastomer resin. Preferably, the high polymer 23 is made of amaterial selected from a group consisting of a polyamide resin,polycarbonate, polymethacrylic resin, epoxy resin, phenol resin,polyurethane resin, vinylbenzene resin and acrylic resin. In otherapplications, the second surface 232 of the high polymer 23 is disposedon the bottom layer.

FIG. 5 shows a flow chart of a method for making the polishing padhaving abrasive grains according to the first embodiment of the presentinvention. Referring to FIGS. 2 and 5, first, in Step S51, a fiber rawmaterial (not shown) is provided, and a spinning step is performed, suchthat the fiber raw material forms a plurality of fibers 21. Preferably,the spinning step is melt spinning, dry spinning or wet spinning. Inthis embodiment, the fibers 21 are solid (as shown in FIG. 3). In otherapplications, the fibers 21 may be hollow (as shown in FIG. 4).Preferably, the fibers 21 have a size of 0.001 to 6 denier. Preferably,the fibers 21 are made of a material selected from a group consisting ofa polyamide resin, PET, polyester resin, nylon, PP, acrylic resin andpolyacrylonitrile resin.

Next, in Step S52, a plurality of abrasive grains 22 is provided, andthen attached to surfaces of the fibers 21 (as shown in FIGS. 3 and 4).In other applications, each of the abrasive grains 22 is exposed to thesurfaces of the fibers 21; that is, each of the abrasive grains 22 ispartially disposed inside the fibers 21 and partially exposed to thesurfaces of the fibers 21. Alternatively, a portion of the abrasivegrains 22 are disposed inside the fibers 21, and a portion of theabrasive grains 22 are exposed to the surfaces of the fibers 21 (asshown in FIGS. 7 and 8). Preferably, the abrasive grains 22 are made ofa material selected from a group consisting of SiO₂ CeO₂, Al₂O₃, oxidesof transition metals and oxides of Group IIA metals.

Afterward, in Step S53, a drawing step is performed, such that thefibers 21 form a fiber matrix 24. In this embodiment, the fiber matrix24 is a non-woven fabric. Preferably, the fiber matrix 24 is formed bychemical bonding, thermal bonding, mechanical bonding, dry carding,direct web-forming or wet web-forming. Then, in Step S54, the fibermatrix 24 is immersed in a high-polymer solution (not shown).

Finally, in Step S55, a curing step is performed, such that the fibermatrix 24 is covered with a high polymer 23. The high polymer 23 has afirst surface 231 and a second surface 232. Preferably, a portion of thefibers 21 and a portion of the abrasive grains 22 are exposed to thefirst surface 231 of the high polymer 23. In other applications, in StepS55, the high polymer 23 completely covers the fiber matrix 24.Alternatively, in Step S55, the high polymer 23 completely covers thefiber matrix 24, and in Step S55, the method further comprises a step ofremoving (for example, dressing or abrading) a portion of the highpolymer 23, such that a portion of the fibers 21 and a portion of theabrasive grains 22 are exposed to the first surface 231 of the highpolymer 23. Preferably, after Step S55, the method further comprises astep of forming a bottom layer on the second surface 232 of the highpolymer 23, in which the bottom layer is a glue layer.

FIG. 6 shows a schematic view of a polishing pad having abrasive grainsaccording to a second embodiment of the present invention. The polishingpad 3 of this embodiment is substantially the same as the polishing pad2 (FIG. 2) of the first embodiment. This embodiment is different fromthe first embodiment in that the abrasive grains 32 are disposed insidethe fibers 31. In this embodiment, the fibers 31 are solid, the abrasivegrains 32 are disposed inside the fibers 31, and a portion of theabrasive grains 32 are exposed to surfaces of the fibers 31 (as shown inFIG. 7). However, in other applications, the fibers 31 may be hollow (asshown in FIG. 8).

FIG. 9 shows a flow chart of a method for making the polishing padhaving abrasive grains according to the second embodiment of the presentinvention. Referring to FIGS. 6 and 9, first, in Step S91, a fiber rawmaterial (not shown) and a plurality of abrasive grains 32 are provided,and the abrasive grains 32 are added into the fiber raw material.Preferably, the abrasive grains 32 are made of a material selected froma group consisting of SiO₂ CeO₂, Al₂O₃, oxides of transition metals andoxides of Group IIA metals.

Next, in Step S92, a spinning step is performed, such that the fiber rawmaterial forms a plurality of fibers 31, in which a portion of theabrasive grains 32 are disposed inside the fibers 31, and a portion ofthe abrasive grains 32 are exposed to the surfaces of the fibers 31 (asshown in FIGS. 7 and 8). Preferably, the spinning step is melt spinning,dry spinning or wet spinning. In this embodiment, the fibers 31 aresolid (as shown in FIG. 7). In other applications, the fibers 31 may behollow (as shown in FIG. 8). Preferably, the fibers 31 have a size of0.001 to 6 denier. Preferably, the fibers 31 are made of a materialselected from a group consisting of a polyamide resin, PET, polyesterresin, nylon, PP, acrylic resin and polyacrylonitrile resin.

Afterward, in Step S93, a drawing step is performed, such that thefibers 31 form a fiber matrix 34. In this embodiment, the fiber matrix34 is a non-woven fabric. Preferably, the fiber matrix 34 is formed bychemical bonding, thermal bonding, mechanical bonding, dry carding,direct web-forming or wet web-forming. Then, in Step S94, the fibermatrix 34 is immersed in a high-polymer solution (not shown).

Finally, in Step S95, a curing step is performed, such that the fibermatrix 34 is covered with a high polymer 33. The high polymer 33 has afirst surface 331 and a second surface 332. Preferably, a portion of thefibers 31 and a portion of the abrasive grains 32 are exposed to thefirst surface 331 of the high polymer 33. In other applications, in StepS95, the high polymer 33 completely covers the fiber matrix 34.Alternatively, in Step S95, the high polymer 33 completely covers thefiber matrix 34, and in Step S95, the method further comprises a step ofremoving (for example, dressing or abrading) a portion of the highpolymer 33, such that a portion of the fibers 31 and a portion of theabrasive grains 32 are exposed to the first surface 331 of the highpolymer 33. The first surface 331 is a polishing surface.

The present invention has the following advantages. During the polishingprocess, due to the flexibility of the fibers 21, 31, the fibers 21, 31that are exposed to the first surface 231, 331 swing as the slurry flowsunder the effect of a stress between the polishing pad 2, 3 and theworkpiece to be polished, such that the abrasive grains 22, 32 attachedthereto also move accordingly instead of being fixed at the sameposition. Thereby, the abrasive grains 22, 32 may not easily scratch thesurface of the workpiece to be polished. In addition, the polishing pad2, 3 achieves a desirable polishing capability with the assistance of anacid or alkali slurry containing no abrasive grains or an electrolyticsolution containing an electrolyte, thus avoiding the problem in theprior art that the abrasive grains of the slurry block the pores of thepolishing pad. Moreover, after the polishing pad 2, 3 is used in thepolishing process, only a small number of abrasive grains 22, 32 areleft on the surface of the workpiece to be polished, which can be easilywashed away by a simple rinsing procedure, and the wastewater may alsobe easily treated.

Examples are given below to illustrate the present invention, and thepresent invention is not limited thereto.

Example

The method of this example corresponds to that of the second embodiment.Referring to FIG. 6, first, a fiber raw material and a plurality ofabrasive grains 32 are provided, and the abrasive grains 32 are addedinto the fiber raw material. The fiber raw material contains 57 wt % ofPET and 40 wt % of polyethylene (PE), and the abrasive grains 32 are 3wt % of SiO₂.

Next, a spinning step is performed, such that the fiber raw materialforms a plurality of fibers 31. The fibers 31 are solid, a portion ofthe abrasive grains 32 are disposed inside the fibers 31, and a portionof the abrasive grains 32 are exposed to the surfaces of the fibers 31(as shown in FIG. 7). The spinning step is melt spinning. In this step,the fiber raw material first passes through an extruder and is melted at288° C., spun from a spinneret, and then cooled at 22° C. The spinningspeed is 550 m/min. Afilament is obtained, which is then cut into shortfibers to form the fibers 31.

Afterward, a drawing step is performed, such that the fibers 31 form afiber matrix 34. The fiber matrix 34 is a non-woven fabric. Then, thefiber matrix 34 is immersed in a high-polymer solution (not shown). Thehigh-polymer solution is made of a material selected from a groupconsisting of a polyamide resin, polycarbonate, polymethacrylic resin,epoxy resin, phenol resin, polyurethane resin, vinylbenzene resin andacrylic resin.

Finally, a curing step is performed. First, the fiber matrix 34 immersedin the high-polymer solution is placed in a 22% dimethylformamide (DMF)coagulation bath for coagulation, then placed in a rinsing bath to washaway the DMF, and dried at 150° C., so as to obtain a polishing pad 3having the abrasive grains 32. Thereby, the fiber matrix 34 is coveredwith a high polymer 33. The high polymer 33 has a first surface 331 anda second surface 332. A portion of the fibers 31 and a portion of theabrasive grains 32 are exposed to the first surface 331 of the highpolymer 33.

While several embodiments of the present invention have been illustratedand described, various modifications and improvements can be made bythose skilled in the art. The embodiments of the present invention aretherefore described in an illustrative but not restrictive sense. It isintended that the present invention should not be limited to theparticular forms as illustrated, and that all modifications whichmaintain the spirit and scope of the present invention are within thescope defined in the appended claims.

1. A polishing pad having abrasive grains, comprising: a plurality offibers, intersecting each other to form a fiber matrix; a plurality ofabrasive grains, attached to the fibers; and a high polymer, coveringthe fibers and the abrasive grains.
 2. The polishing pad according toclaim 1, further comprising a bottom layer, wherein a second surface ofthe high polymer is disposed on the bottom layer.
 3. The polishing padaccording to claim 1, wherein the fiber matrix is a non-woven fabric. 4.The polishing pad according to claim 1, wherein the fibers are solid orhollow and the fibers are made of a material selected from a groupconsisting of a polyamide resin, polyethylene terephthalate (PET),polyester resin, nylon, polypropylene (PP), acrylic resin andpolyacrylonitrile resin.
 5. The polishing pad according to claim 1,wherein the abrasive grains are disposed inside the fibers, and aportion of the abrasive grains are exposed to surfaces of the fibers. 6.The polishing pad according to claim 1, wherein the abrasive grains aredisposed on the surfaces of the fibers.
 7. The polishing pad accordingto claim 1, wherein the abrasive grains are made of a material selectedfrom a group consisting of SiO₂, CeO₂, Al₂O₃, oxides of transitionmetals and oxides of Group IIA metals.
 8. The polishing pad according toclaim 1, wherein the high polymer has a first surface and a secondsurface, and a portion of the fibers and a portion of the abrasivegrains are exposed to the first surface.
 9. The polishing pad accordingto claim 1, wherein the high polymer is made of a material selected froma group consisting of a polyamide resin, polycarbonate, polymethacrylicresin, epoxy resin, phenol resin, polyurethane resin, vinylbenzene resinand acrylic resin.
 10. The polishing pad according to claim 1, whereinthe high polymer is an intercommunicated porous high-polymeric elastomerresin.
 11. A method for making a polishing pad having abrasive grains,comprising: (a) providing a fiber matrix, wherein the fiber matrix has aplurality of fibers and a plurality of abrasive grains, the fibersintersect each other, and the abrasive grains are attached to thefibers; (b) immersing the fiber matrix in a high-polymer solution; and(c) performing a curing step, such that the fiber matrix is covered witha high polymer.
 12. The method according to claim 11, wherein Step (a)comprises: (a1) providing a fiber raw material, and performing aspinning step, such that the fiber raw material forms a plurality offibers; (a2) providing a plurality of abrasive grains, and attaching theabrasive grains to surfaces of the fibers; and (a3) performing a drawingstep, such that the fibers form the fiber matrix.
 13. The methodaccording to claim 12, wherein in Step (a1), the spinning step is meltspinning, dry spinning or wet spinning.
 14. The method according toclaim 11, wherein Step (a) comprises: (a1) providing a fiber rawmaterial and a plurality of abrasive grains, and adding the abrasivegrains into the fiber raw material; (a2) performing a spinning step,such that the fiber raw material forms a plurality of fibers, wherein aportion of the abrasive grains are disposed inside the fibers, and aportion of the abrasive grains are exposed to the surfaces of thefibers; and (a3) performing a drawing step, such that the fibers formthe fiber matrix.
 15. The method according to claim 14, wherein in Step(a2), the spinning step is melt spinning, dry spinning or wet spinning.16. The method according to claim 11, wherein in Step (a), the fibersare solid or hollow.
 17. The method according to claim 11, wherein inStep (a), the abrasive grains are made of a material selected from agroup consisting of SiO₂ CeO₂, Al₂O₃, oxides of transition metals andoxides of Group IIA metals.
 18. The method according to claim 11,wherein in Step (a), the fiber matrix is a non-woven fabric, and isformed by chemical bonding, thermal bonding, mechanical bonding, drycarding, direct web-forming or wet web-forming.
 19. The method accordingto claim 11, wherein Step (c) further comprises a step of removing aportion of the high polymer, such that a portion of the fibers and aportion of the abrasive grains are exposed to a first surface of thehigh polymer.
 20. The method according to claim 11, wherein after Step(c), the method further comprises a step of forming a bottom layer on asecond surface of the high polymer.